This invention relates to seals, and more particularly to seal constructions useful in hydraulic couplings and the like wherein an internal liquid pressure is maintained above an external pressure.
A variety of annular seals suitable for the sealing of fluid conduits exist. One common seal is the NAFLEX seal, a self-biasing metallic seal.
One application for annular seals lies in the field of hydraulics, particularly in hydraulic couplings used in the undersea oil drilling industry. In that industry, complex arrangements of valves, known as xe2x80x9cChristmas treesxe2x80x9d are hydraulically actuated from the above-water portion of an associated drilling rig. Long hydraulic fluid lines extend from the rigs to the xe2x80x9cChristmas treesxe2x80x9d and are connected thereto by means of quick connect/disconnect hydraulic couplings. Examples of such couplings are disclosed in U.S. Pat. No. 5,482,082 of Edwin C. Turner and Danny K. Wolff, the disclosure of which is incorporated herein by reference in its entirety. Turner et al. discloses the use of a first group of annular seals carried within the housing of female coupling moiety and a second group of seals carried within a closure slide of the mating male coupling moiety. The seals of the first group are of modified NAFLEX design whereas the seals of the second group have a cross-sectional profile largely radially inverted relative to that of the first group.
Many other seal constructions exist. Among these, are polymeric seals. One group of polymeric seals is spring energized polymeric seals. These include seals utilizing a helical metallic energizing spring. An example of a spring-energized polymeric seal is shown in European Patent Application EP 0867647 of John Crane, U.K. Limited.
In one aspect, the invention is directed to an apparatus for forming a seal between first and second conduits. The apparatus may be formed in two halves mated along a transverse center plane. Each half may face outward from an associated side of the center plane and may include a centrally apertured metal body. The metal body has an outwardly projecting hub having an outward-facing engagement surface. A web extends radially outward from the hub to a perimeter and has interior and exterior surfaces. The two bodies are secured to each other such as by an annular weld so that their combination forms a seal body. A longitudinal separation between the engagement surfaces is compressible via a flexing of the webs from a relaxed separation to a range of compressed separations. In the compressed separations, the surfaces are sealingly engaged to respective ones of the first and second conduits.
In various implementations, the metal bodies may consist essentially of a nickel superalloy plated with a more malleable material such as gold, silver or copper. The seal may optionally include an annular stop sleeve having opposite ends within the hubs of the seal bodies. A sleeve length may be less than the relaxed separation but greater than a combination of the hub lengths so as to prevent compression of the longitudinal separation below a safe minimum value whereby damage to the seal may be avoided.
In another aspect, the invention is directed to an apparatus for forming a seal between first and second elements. The apparatus includes first and second annular polymeric sealing members, each having a first surface for sealingly engaging the first element and a second surface for sealingly engaging the second element. An annular retaining member has an annular cap portion having an inboardmost portion covering a portion of the first sealing member outboard of the first surface of the first sealing member. An outboardmost portion of the annular cap portion covers a portion the sealing member inboard of the first surface of the second sealing member. The retaining member includes at least one annular collar portion depending from the cap portion and directed toward the second element.
In various implementations, an additional annular collar portion formed integrally with the second element may be intermeshed with at least one collar portion of the annular retaining member and project toward the cap portion thereof. First and second such collar members of the annular retaining member may be intermeshed with one such additional collar member between them. Such an apparatus may provide a seal between a seal body and a valve body in a valve. A pair of such apparatus may provide a seal system, the second elements being provided by first and second halves of a metallic seal body and the first elements being the two elements to be sealed by the seal system.
Among the advantages of the invention is enhanced longitudinal compactness. The two-piece welded construction allows the disks to be located closer together than in a similar one-piece NAFLEX construction. This longitudinal compactness further facilitates the addition of the polymeric sealing rings on one or both sides of the seal.